I've gone and installed a Borla R50 exhaust on my 03 Cooper S. I'll let you in on my reasoning. The double muffler setup always bothered me. It seems very unnecessary and complicated as well as heavier than it needs to be. It's really more of a styling exercise than a performance increase. I installed a hitch on my car but because of the center exit exhaust I could never get the pin through the hitch. Luckily my bike rack uses a wedge arrangement you tighten externally with a ****. It figure it won't effect performance at all. The Borla uses the same size piping as the stock S system but with a whole lot less bends. If anything it should flow better.

Now onto my question. I purchased a rear valance for the bumper for an 03 base model. All the mounting tabs lined right up but it is ~1/2" shorter in vertical height than the S version. I looked at the Mini Atlanta online parts fiche and there seems to be only one version for the base model. I read on the non-s part of the forum that people were using the S trim on their cars with no trouble. I didn't see any part numbers referenced. Just to use the pre facelift version. Which is what I did in reverse. Anyone have any idea if any version of the base model lower valance will line up with my S bumper?

I've cut the bumper trim for now but would really like to lose the center cutout. Here is a picture of it(excuse the dirt it rained today)-

 

See here for more info on this swap- https://www.northamericanmotoring.co...-question.html

 

I did this a few years back, only I did a custom exhaust.
You need the side trim pieces off an R50 as well:

#3 in pic. part #51126800225 & 51126800226

 

Thank you so much! Ordered.

 

Welcome. Good idea on the Justa aftermarket exhaust, I never got my "custom" the way I liked it. Will consider this when my JCW cat back dies.

 

I've got all the R50 bumper parts mounted up now. I really like the way it looks. Anyone who knows anything about Minis is going to be a bit puzzled by my car. I now have the R50 single exhaust, R50 gas filler cover and the black R50 side scuttle trims.

 

That looks really good.